Functionalization of Carbon Nanotubes

Albeit initially reported by a Russian group and reported again by Oberlin and co-workers (Oberlin et al., 1976), carbon nanotubes (CNTs) were first brought to the attention of greater scientific community by Ijima in 1991. It was not until 1991 that CNTs came to limelight unfolding its exotic properties. Following this report, academic interest in this onedimensional nanomaterial has grown remarkably and phenomenal number of research are being carried out worldwide. Its outstanding properties such as high mechanical strength, flexibility and impressive electrical and thermal conductivity make itself attractive and potential candidate for various applications. Despite CNTs’s exceptional properties, there are two main limitations that hinder its use. The surface energy of CNTs is significantly different from that of matrices such as common organic solvents or polymers and CNTs may not have chemical affinity to the organic matrices and thus, the dispersion of CNTs into matrices is the biggest obstacle in practice (Song et al., 2005). In addition, the seamless surface of CNTs cannot provide physical interaction between CNTs and matrix (Ajayan et al., 2000). The modification of CNTs with other materials, makes it the most attractive and ultimate candidate for a plethora of applications which includes nanodevices, to organic electronics. In terms of the practical challenges that must be addressed to expand CNTs application scope in various potential fields of nanotechnology; many protocols have been proposed and considerable amount of research work is being focused on the interfacial molecular engineering of CNTs, aiming at improving their state of interaction with macromolecules, mainly to optimize the final properties of the hybrid nanomaterials. These protocols to prepare such hybrid composites have triggered burgeoning interest and to realize most of these applications practically, CNTs are most frequently functionalized with various kinds of technologically important polymers to improve the properties of the end material. Such assemblies have already suggested that the functionalization of polymers to CNTs draws equal importance in materials development for future applications in constructing optoelectronic devices. This chapter will focus and discuss the frequently used methods to functionalize CNTs namely; covalent and non-covalent strategies. Of particular importance, this chapter will also shed light on the ‘pros and cons’ of the frequent methods and alternative methods that have been developed in the recent past which can open the